System for suspending a color selection electrode in a color cathode ray tube

ABSTRACT

This disclosure depicts a system for suspending a color selection electrode on the envelope of a color cathode ray tube at a predetermined precise spacing from a faceplate portion of the envelope. The suspension system includes a plurality of highly compact suspension devices spaced around the electrode, each device comprising envelope-mounted means secured in a precise location on the inside of the envelope, and electrodemounted means for retentively engaging the envelope-mounted means. The electrode-mounted means is depicted as comprising rigid bracket means secured to the electrode, the bracket means including or constituting a bimetallic element which, upon heating of the electrode, deflects to cause the electrode to move nearer to the faceplate portion of the envelope. The electrodemounted means also includes a spring supported by the bracket means and means for retentively engaging the envelope-mounted means.

United States Patent [1 1 Sedivy July 22, 1975 [75] Inventor: Stanley J.Sedivy, Chicago Ridge,

[73] Assignee: Zenith Radio Corporation, Chicago,

221 Filed: Dec. 12, 1973 21 Appl. No.: 424,017

FOREIGN PATENTS OR APPLICATIONS 45-32495 1970 Japan 313/85 S PrimaryExaminer Robert Segal Attorney, Agent, or Firm.lohn H. Coult [57]ABSTRACT This disclosure depicts a system for suspending a colorselection electrode on the envelope of a color cathode ray tube at apredetermined precise spacing from a faceplate portion of the envelope.The suspension system includes a plurality of highly compact suspensiondevices spaced around the electrode, each device comprisingenvelope-mounted means secured in a precise location on the inside ofthe envelope, and electrode-mounted means for retentively engaging theenvelope-mounted means. The electrode-mounted means is depicted ascomprising rigid bracket means secured to the electrode, the bracketmeans including or constituting a bimetallic element which, upon heatingof the electrode, deflects to cause the electrode to move nearer to thefaceplate portion of the envelope. The electrode-mounted means alsoincludes a spring supported by the bracket means and means forretentively engaging the envelope-mounted means.

14 Claims, 7 Drawing Figures SHEET PATENTEDJUL 2 2 I975 PATENTEDJUL 2 2I975 SHEET PO @OQOQQ OOQCQOOO SYSTEM FOR SUSPENDING A COLOR SELECTIONELECTRODE IN A COLOR CATIIODE RAY TUBE CROSS REFERENCE TO RELATEDAPPLICATIONS This application is related to, but in no way dependentupon, copending applications including Ser. No. 395,334,,filed Sept. 7,1973, Ser. No. 395,106, filed Sept. 7, 1973 now abandoned, and Ser. No.285,985, filed Sept. 5, 1972, all assigned to the assignee of thepresent invention.

BACKGROUND OF THE INVENTION This invention relates to color cathode raytubes of the type having a color selection electrode, and especially toa system for suspending a color selection electrode in a color tube.

Conventional shadow mask-type color tubes have a shadow mask assemblywhich comprises a rigid frame upon which is welded a thin, sphericallyshaped mask having a pattern of electron-transmissive apertures formedtherein. The mask assembly is suspended in the tube by a set of leafsprings welded to the sides of the mask frame, usually three in number,which engage studs extending inwardly from a flange on a front panel ofthe tube.

The present invention has wide-spread applicability, but is particularlyuseful for suspending a low cost, frameless, flexible color selectionelectrode of novel construction, described in detail and claimed in thereferent copending application Ser. No. 395,334. As described andclaimed in another of the referent copending applications, Ser. No.285,985, it is preferable to mount a mask of the character described atits four corners, rather than at the sides as is conventional. Whereasthe teachings of this invention are applicable for mounting colorselection electrodes of other types than the shadow mask mentioned, andin arrangements other than four corner suspension configurations, theinvention appears to have greatest utility for suspending a framelessmask of the character described.

In the interest of promoting automation of the operation in which acolor selection electrode is mounted in a tube, it is desirable that anelectrode suspension system be capable of automated or semi-automatedmounting. Further, any commercially practicable color selectionelectrode suspension system must compensate for thermally inducedvariations in the electrode Q spacing, that is, the critical spacingbetween the electrode and the phosphor screen. The Q spacing must beaccurately maintained in order to preserve registration between theelectron beam landing spots and the impinged phosphor elements.

Still further, because of the extreme penalty which must be paid inbulk, weight, and cost for unnecessarily large envelopes, it is highlydesirable that an electrode suspension system take up a minimum amountof space in the envelope to permit use of the smallest envelope sizepossible. Yet another constraint on electrode suspension systems is therequirement that the points of electrode suspension be determinable withextreme precision in order that the electrode, when mounted, will assumea precise spatial relationship to the phosphor pattern on the faceplateof the tube. Still another extremely important consideration is the costof manufacture of an electrode suspension system.

The described electrode suspension system constraints and requirementsconverge in a system such as the above-characterized preferredembodiment wherein the suspension devices are located at the fourcorners of the electrode and wherein cost is a paramount consideration.In a conventional electrode suspension system wherein the electrodesuspension devices are located at the sides of the electrode, adequateunused space is available for placement of the suspension devices. Thereason for this lies in the fact that in a conventional (rectangular)color cathode ray tube, the sides of the tube bulge outwardly, creatingmedial spaces along the sides of the electrode in which the suspensiondevices can be located. In an electrode suspension system of the typewith which this invention is concerned, the suspension devices arelocated in the corners of the tube where available space is verylimited.

OTHER PRIOR ART J. H. Duistermaat et al J. H. Duistermaat et al J.Driedijk et al OBJECTS OF THE INVENTION It is a general object of thisinvention to provide an improved system for suspending a rectangularcolor selection electrode in a color cathode ray tube.

It is a less general object of this invention to provide an improvedsuspension system for a color selection electrode which is adaptable forsuspending a frameless flexible color selection electrode at the fourcorners thereof.

It is another object to provide such an electrode suspension system inwhich the constituent suspension devices are extremely compact and arethus particularly suited for comer mounting a color selection electrode.

It is yet another object to provide such a suspension system which iscapable of supporting a color selection electrode directly upon thefaceplate of a color cathode ray tube envelope, or alternatively, uponthe flange of a flanged-type cathode ray tube front panel.

It is still another object to provide a color selection electrodesuspension system having the above-noted properties and features, andyet which is extremely accurate in its location of the electrode andrelatively inexpensive to manufacture.

It is still another object to provide a suspension system for a colorselection electrode which is capable of thermally compensating theelectrode to maintain an appropriate Q spacing, and which does notintroduce any thermally induced rotation of the electrode relative tothe tube envelope.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the invention whichare believed to be novel and unobvious are set forth with particularityin the appended claims. The invention, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of a novel color cathode ray tube as seenfrom the rear, with a portion of the envelope cut away to reveal asuspension system for a color selection electrode which implements theprinciples of this invention;

FIG. 2 is an elevational view of the FIG. 1 tube, cut away to show themask and its suspension system;

FIG. 3 is an enlarged perspective view of a mask suspension device shownin FIGS. l2;

FIG. 4 is an exploded view of the mask suspension device illustrated inFIG. 3;

FIG. 5 is an enlarged sectioned elevational view of the mask suspensiondevice shown in FIGS. 3 and 4;

FIG. 6 is a perspective view, partly broken away, of another embodimentof this invention; and

FIG. 7 is a sectional view taken along lines 77 in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention is directed toproviding an improved system for suspending a generally rectangularcolor selection electrode on the envelope of a rectangular-type colorcathode ray tube. The suspension system of this invention may be used tosuspend a color selection electrode in color cathode ray tubes ingeneral which are of the type requiring such an electrode, however it isespecially useful for suspending upon the envelope of a color tube anovel, lightweight, flexible shadow mask as described and claimed in thereferent copending application Ser. No. 395,334. The system includes aplurality of suspension devices spaced around the electrode; in apreferred embodiment the system includes four suspension devices, one ateach corner of the electrode. The lightweight, flexible mask alluded toabove is adapted to be supported at its corners so as to permit it toconform to the contour of a cathode ray tube faceplate which it ismounted adjacent. This mask is described and claimed, per se, in theabove-noted copending application, Ser. No. 285,985.

FIGS. 1-5 illustrate a color cathode ray tube 10 incorporating a systemaccording to this invention for suspending a color selection electrode,illustrated as taking the form of a shadow mask 11. The tube 10 isdepicted as having an envelope with a novel construction comprising afunnel l2 sealed to a generally rectangular, flangeless faceplate 14.

The mask 11 is illustrated as being of a low cost, lightweight,frameless, flexible character, being preferably formed integrally from asingle sheet of electrically conductive material such as steel, all asdescribed in detail and claimed in the referent copending applicationSer. No. 395,334. The mask 11 is illustrated as having a curved centralportion 18 which has formed therein a pattern of electron-transmissiveapertures 20. The mask 11 includes a strengthening channel 22surrounding and joined with the central portion 18.

The mask 11 has a skirt 24 of generally constant depth surrounding andjoined with the channel 22. The skirt 24 includes a forwardly directed,outwardly flared body portion terminating in a leading edge portion 28.As described in detail in the referent copending application, theconfiguration of the strengthening channel 22 and of the skirt 24 issuch as to enhance the strength of the mask and to shield, to themaximum degree possible, the phosphor screen 29 on the inner surface ofthe faceplate 14 from stray or overscanned electrons emanating fromelectron guns (not shown) in the neck of the tube 10.

The flared body portion of the skirt 24 has formed along each side aplurality of strengthening ribs 30. The ribs on each side of the mask 11are individually straight, mutually parallel and orthogonal to the tubeaxis. The ribs 30 are effective to substantially synthesize aload-bearing beam having an effective loadbearing depth which is greaterthan the depth of any individual rib element 30.

This invention is especially concerned with the provision of a compact,low cost suspension system for corner-suspending a color selectionelectrode, such as a shadow mask'll, adjacent the faceplate portion of acathode ray tube. The illustrated preferred system comprises a pluralityof mask suspension devices 32, one located at each comer of the mask 11.The mask suspension devices 32 according to this invention each compriseenvelope-mounted means, here shown as taking the form of a stud 34,secured in a precise location on the inside of the tube envelope. In theillustrated preferred embodiment, the stud 34 is shown as comprising abody 36 and a foot 38. The foot 38 is cemented, as by means of afrit-type cement, to the inner surface of the faceplate 14.Alternatively, it may be embedded in or otherwise secured to thefaceplate 14.

Each suspension device 32 includes electrodemounted means forretentively engaging the envelopemounted means (here shown as the stud34). In the illustrated preferred embodiment, the electrodemounted meansis shown as comprising a rigid bracket 40 having an intermediate portionexternally surrounding and embracing a corner of the mask 11. Thebracket 40 is secured at opposite ends 42, 44 to adjoining sides of themask 1 l. The electrode-mounted means further includes coupling meanssupported by the bracket 40 which comprises a discrete spring 46 andmeans (to be described) for engaging the stud 34.

In the illustrated preferred embodiment, the bracket 40 comprises twostrips of metal which have different coefficients of thermal expansionand which are edgebonded together. The bracket 40 deflects, upon heatingof the mask 11, to cause the mask 11 to move nearer to the faceplate 14so as to provide Q- compensation. By selecting strip materials to have apredetermined difference in thermal coefficient of expansion, and byselecting the length of the bracket arms 48, 50 appropriately long, agiven amount of temperature increase in the electrode will produce anappropriate translation of the mask 11 to effect Q- compensation. Thatis to say, the mask 11 will be translated nearer to the faceplate 14 adistance effective to maintain registration between the electron beamlandings and the phosphor elements constituting the phosphor screen 29.

In accordance with a preferred implementation of the invention, the stud34 has a lug-receiving opening 52 formed therein which is adapted toreceive a lug 54 carried by the spring 46. The body 36 of the stud 34also includes a guide channel 56 for assisting in mounting the mask 11in the tube 10. Apparatus which employs a guide channel to provide forautomated or semi-automated mask mounting is described and claimed, perse, in my referent copending application Ser. No. 395,106.

In accordance with one aspect of this invention, the spring 46, whichmay be characterized as a foldedback leaf spring preferably has areverse bend defining a first leg 58 which is secured to the bracket 40and an opposed second leg 60 which carries the lug 54. The leg 58 isbifurcated into two parts 62, 64 which straddle a lug-passing opening 66in the bracket 40 located on a diagonal of the electrode. As shown withparticular clarity in FIGS. 3 and 5, the lug 54 is secured to leg 60 andextends from the out-facing side thereof through the lug-passing opening66 in the bracket 40 for retentive engagement with the lug-receivingopening 52 in the stud 34 when the mask 11 is operatively mounted in thetube 10.

The suspension device 32, by the novel construction above'described, hasthe following desirable properties. First, the suspension device isextremely compact, owing in large part to the use of the reverse bent orfolded-back spring 46 which arches inwardly from the bracket 40 andwhich deflects in the unused space above the flared skirt 24 on the mask11. Second, the spring 46 is protected against possible damage duringhandling of the mask. Third, by the disclosed arrangement wherein onlythe spring-biased lug 54 extends beyond the bracket, the suspensiondevice is highly suited to an automated or semi-automated mask mountingoperation. Fourth, by the use of a rigid bracket 40 to which is securedspring 46, economies in the fabrication of the. suspension device areachieved, since the bracket 40 can be welded to the mask 1 1 in a loosetolerance attachment operation and the spring 46 subsequently attachedprecisely to the bracket by a tight tolerance attachment operation. Thelatter attachment operation (welding, for example) is much easier tohold tolerances on than the operation in which the bracket 40 is securedto the mask 11.

To enhance the engagement/disengagement characteristics of the lug 54and the stud 34, the lug-receiving opening 52 is preferably generallytriangular in shape with rounded comers such that the lug 54 makes athree-point engagement with the opening 52. Further to this end, the lug54 preferably has at least two sections of increasing taper toward thedistal end of the lug 54, or one section of taper and a radius tangentto taper at the small end of the lug. In the illustrated preferredembodiment, two sections 68, 70 of increasing taper are shown.

As discussed above, due to the need for an extremely compact suspensiondevice when corner mounting is employed, it is desirable that the spring46, which functions in part to permit disengagement of the lug 54 fromthe stud 34, require a minimum travel in order to effect the saiddisengagement. Further, it is necessary in order to preclude excessivevibration of the mask 11 during operation of the tube, and in order toresist excessive mechanical shocks during handling of the tube (whichmay reach 40 Gs or more), that the suspension devices 32 each exert apredetermined firm loading force on the mask, e.g., in the order of 2.0pounds. It is desirable, however, that any loading spring employed notbe so stiff as to overload the mask when the tube is baked duringassembly or when the tube is operating at maximum operatingtemperatures. It is also desirable that any such loading spring apply apredetermined load to the mask which is relatively constant within arelatively broad tolerance range.

With these objectives and difficulties considered, according to oneaspect of this invention, the spring 46 has the afore-described reversebent, inwardly arched construction and is preferably pre-stressed suchthat the leg 60 exerts a load on the bracket 40 when the device is notsuspending the mask which is substantially equal to the desired loadingof the mask by the spring when the mask is mounted in the tube. Second,prestressing of the spring 46 permits the use of a relatively low ratespring. The use of a low rate spring which is pre-stressed has theresult that the load which is applied to the mask when mounted in atube, can be predetermined with lower required tolerances since theassociated force-versus-displacement characteristic thereof isrelatively shallow. The lower tolerances associated with the relativelylow rate spring also imply that the loading of the mask 11 is moreconstant over a wider range of spring deflections than would be the caseif a relatively stiff spring were employed. The lower tolerancespermitted by the use of a relatively low rate spring also result ineconomies in manufacture of the device 32.

To mount the mask 11 in the tube 10, a mounting instrumentality oroperator merely aligns the lugs 54 with the guide channels 56 in thestuds 34 and translates the mask forwardly until the lugs 54 snap intoplace in the lug-receiving openings 52 in the studs 34.

To remove the mask from the tube 10, the spring member 46 is expanded tocause the lug 54 to be withdrawn from the lug-receiving opening 52 andthereby permit the mask 11 to be withdrawn.

A mask suspension system comprising four mask suspension devices havingthe construction shown at 32 was built according to the followingspecifications and was tested with success in achieving certain majorobjectives.

In each device 32, the bracket 40 took the form of edge-bonded strips ofinvar and high expansion alloy 22-3 (carpenter) 3/16 inch (for eachmaterial) in thickness and .030 inch in width. The bracket 40 was 2.5inches long and was welded to the mask skirt 24 at its opposite ends.The spring 46 was composed of stainless steel alloy 17-7, .015 inch inthickness and was welded upon the center section of the bracket 40. Thespring was pro-stressed with a load of 1-2 pounds. The lug extended .200inch from the leg 60, had a diameter of .203 at contact with body 36 andtaper angles of 30 (included) and 60 (included). The stud 34 wasmachined from 430 titanium stainless steel stock and was frit-cementedto the inner surface of the faceplate 14. Satisfactory mask loadingcharacteristics and Q- compensation were achieved.

In accordance with this invention, the electrodemounted means includes arigid bracket which includes a Q-compensating bimetallic member andwhich carries a spring and provision for engaging the stud 34. Whereasin the illustrated preferred embodiment the bracket is formed as asingle edge-bonded bimetallic strip, it is contemplated that thebimetallic member and the means for securing the member to the colorselection electrode may be separate structures. Such a construction isincorporated in the FIGS. 6 and 7 embodiment, described below. Further,whereas the FIGS. 1-5 embodiment has been shown as being adapted forsuspending a color selection electrode directly on the faceplate of acolor tube which has an envelope consisting of a funnel and a flangelessfaceplate, the principles of this invention are equally useful forsuspending a color selection electrode on a color tube envelope of theconventional type including a flanged front panel.

FIGS. 6-7 illustrate an embodiment of the invention implementing thismodification also.

FIGS. 6 and 7 depict a suspension device 72 for suspending a colorselection electrode 74 adjacent the face-plate portion 76 of a frontpanel 78 having a flange 80. The mask suspension device 72 is generallysimilar to the device 32 described above, with the below-notedexceptions.

The bracket, rather than comprising a single bimetallic strip, has threeparts a bimetallic strip 82 and bracket members 84, 86 for securing thestrip 82 to the flared skirt 88 of the electrode 74. By thisarrangement, the bimetallic strip 82 can be mounted without any bends ordistortions along its length. The bracket members 84, 86 may be weldedto the electrode 74 and to the bimetallic strip 82 to secure the stripto the electrode 74.

In order to permit mounting of the color selection electrode 74 on theflange 80 of a conventional color cathode ray tube front panel 78, amodified stud 90 may be provided. The stud 90 is illustrated ascomprising a body 92, which may be substantially identical to the body36 of the stud 34, and a foot 92 which is adapted to be embedded in theflange 80 by wellknown stud embedding techniques. The stud embeddingoperation is performed while the front panel 78, or a localized portionthereof, is warm and soft.

The invention is not limited to the particular details of constructionof the embodiments depicted and other modifications and applications arecontemplated. Certain changes may be made in the above-describedapparatus without departing from the true spirit and scope of theinvention herein involved and it is intended that the subject matter inthe above depiction shall be interpreted as illustrative and not in alimiting sense.

I claim:

1. For use in a rectangular-type color cathode ray tube, a system forsuspending a generally rectangular color selection electrode having apattern of electrontransmissive apertures on the envelope of the tube ata predetermined'precise spacing from a faceplate portion of the envelopebearing a corresponding pattern of redemissive, blue-emissive andgreen-emissive phosphor element triads, including four electrodesuspension devices spaced around the electrode, one at each cornerthereof, each device comprising:

envelope-mounted means secured in a corner location on the inside of theenvelope for supporting a corner of a color selection electrode; and

electrode-mounted means for retentively engaging said envelope-mountedmeans, comprising:

a bracket having an intermediate portion externally surrounding andembracing a corner of the electrode and end portions secured toadjoining sides of the electrode, and

coupling means including a folded-back leaf spring having one legsecured to said intermediate portion of said bracket and archingradially inwardly therefrom, said coupling means including a provisionon an opposed leg of said spring for retentively engaging saidenvelope-mounted means.

2. The apparatus defined by claim 1 wherein said intermediate portion ofsaid bracket includes an edgebonded bimetallic element which, uponheating of the electrode, deflects to cause said electrode to move nearto said faceplate portion of said envelope.

3. The apparatus defined by claim 1 wherein said envelope-mounted meansincludes a metal stud secured to the envelope and having therein alug-receiving opening, and wherein said provision on said opposed leg ofsaid spring comprises a lug for retentively engaging said lug-receivingopening in said stud when the electrode is operatively mounted in thetube.

4. The apparatus defined by claim 3 wherein said intermediate portion ofsaid bracket includes an edgebonded bimetallic strip and wherein saidstrip has a lugpassing opening formed therein on a diagonal of theelectrode through which said lug passes for operative engagement withsaid lug-receiving opening in said stud.

5. The apparatus defined by claim 3 wherein said lug has at least twosections of different taper, the taper increasing toward the distal endof the lug.

6. The apparatus defined by claim 4 wherein said spring is pre-stressedsuch that said opposed leg exerts a load on said strip when said deviceis not suspending an electrode which is substantially equal to thedesired loading of the electrode by said spring when an electrode ismounted in the tube.

7. For use in a rectangular-type color cathode ray tube, a system forsuspending a rectangular color selection electrode having a pattern ofelectron-transmissive apertures on the envelope of the tube at apredetermined precise spacing from a faceplate portion of the envelopebearing a corresponding pattern of redemissive, blue-emissive andgreen-emissive phosphor element traids, including four electrodesuspension devices on the periphery of the electrode, each comprising:

envelope-mounted means secured in a comer location on the inside of theenvelope and on a diagonal of the color selection electrode forsupporting a comer of a color selection electrode; and

electrode-mounted means for retentively engaging said envelope-mountedmeans, comprising:

bracket means secured to said electrode, said bracket means including abimetallic element which, upon heating of the electrode, deflects tocause the electrode to move nearer to said faceplate portion of theenvelope, and

coupling means including a discrete, folded-back leaf spring having oneleg secured to said bracket means and arching radially inwardlytherefrom, said coupling means including a provision on an opposed legof said spring for retentively engaging said envelope-mounted means,three of said suspension devices fixing in the plane of the mask thespatial position of the mask relative to said faceplate portion, and aredundant fourth suspension device having provision for permitting thefourth corner of the mask to seek an equilibrium position in the planeof the mask.

8. The apparatus defined by claim 7 wherein said envelope-mounted meansincludes a stud secured to the envelope on a diagonal of said electrodeand having said stud is a slot elongated in a direction transverse tosaid diagonal but parallel to said faceplate portion of the envelope.

10. The apparatus defined by claim 9 wherein said bracket means has alug-passing opening formed therein through which said lug passes foroperative engagement with said lug-receiving opening in said stud.

11. The apparatus defined by claim 10 wherein said spring ispre-stressed such that said opposed leg exerts a load on said bracketmeans when said device is not suspending an electrode which issubstantially equal to the desired loading of the electrode by saidspring when an electrode is mounted in the tube.

12. For use in a rectangular color cathode ray tube, a system forsuspending on the envelope of the tube at a predetermined precisespacing from a faceplate portion of the envelope which bears a patternof redemissive, blue-emissive and green-emissive phosphor element triadsa generally rectangular, frameless color selection electrode havingformed integrally therewith a forwardly directed skirt angled atapproximately the angle of maximum beam deflection and having a centralregion containing a corresponding pattern of electron-transmissiveapertures, said system including a plurality of electrode suspensiondevices spaced around the electrode, one at each corner thereof, each ofsaid devices comprising:

an envelope-mounted stud secured in a precise location in a corner ofthe faceplate portion of the envelope on a diagonal of the electrode forsupporting a corner of a color selection electrode, said stud having alug-receiving opening on said diagonal;

and electrode-mounted means for retentively engaging said stud,comprising:

bracket means externally surrounding and embracing a corner of theelectrode, said bracket having an intermediate portion and end portionssecured to the angled skirt on adjoining sides of the electrode, saidbracket means including an edgebonded bimetallic strip wrapped aroundthe corner of the electrode on the outside thereof which, upon heatingof the electrode, deflects in its own plane to cause said electrode tomove nearer to the faceplate, and

a folded-back leaf spring having one leg secured to said bimetallicstrip, said spring arching radially inwardly therefrom, the opposed legof said spring carrying a radially outwardly facing tapered lug forretentively engaging said lugreceiving opening in said stud when theelectrode is operatively mounted in the tube.

13. The apparatus defined by claim 12 wherein said bimetallic strip hasa lug-passing opening formed thereon on a diagonal of the electrodethrough which said lug passes for operative engagement with saidlugreceiving opening in said stud.

14. The apparatus defined by claim 13 wherein said spring ispre-stressed such that said opposed leg exerts a load on said strip whensaid device is not suspending an electrode which is substantially equalto the desired loading of the electrode by said spring when an electrodeis mounted in the tube.

1. For use in a rectangular-type color cathode ray tube, a system forsuspending a generally rectangular color selection electrode having apattern of electron-transmissive apertures on the envelope of the tubeat a predetermined precise spacing from a faceplate portion of theenvelope bearing a corresponding pattern of red-emissive, blue-emissiveand green-emissive phosphor element triads, including four electrodesuspension devices spaced around the electrode, one at each cornerthereof, each device comprising: envelope-mounted means secured in acorner location on the inside of the envelope for sUpporting a corner ofa color selection electrode; and electrode-mounted means for retentivelyengaging said envelopemounted means, comprising: a bracket having anintermediate portion externally surrounding and embracing a corner ofthe electrode and end portions secured to adjoining sides of theelectrode, and coupling means including a folded-back leaf spring havingone leg secured to said intermediate portion of said bracket and archingradially inwardly therefrom, said coupling means including a provisionon an opposed leg of said spring for retentively engaging saidenvelope-mounted means.
 2. The apparatus defined by claim 1 wherein saidintermediate portion of said bracket includes an edge-bonded bimetallicelement which, upon heating of the electrode, deflects to cause saidelectrode to move near to said faceplate portion of said envelope. 3.The apparatus defined by claim 1 wherein said envelope-mounted meansincludes a metal stud secured to the envelope and having therein alug-receiving opening, and wherein said provision on said opposed leg ofsaid spring comprises a lug for retentively engaging said lug-receivingopening in said stud when the electrode is operatively mounted in thetube.
 4. The apparatus defined by claim 3 wherein said intermediateportion of said bracket includes an edge-bonded bimetallic strip andwherein said strip has a lug-passing opening formed therein on adiagonal of the electrode through which said lug passes for operativeengagement with said lug-receiving opening in said stud.
 5. Theapparatus defined by claim 3 wherein said lug has at least two sectionsof different taper, the taper increasing toward the distal end of thelug.
 6. The apparatus defined by claim 4 wherein said spring ispre-stressed such that said opposed leg exerts a load on said strip whensaid device is not suspending an electrode which is substantially equalto the desired loading of the electrode by said spring when an electrodeis mounted in the tube.
 7. For use in a rectangular-type color cathoderay tube, a system for suspending a rectangular color selectionelectrode having a pattern of electron-transmissive apertures on theenvelope of the tube at a predetermined precise spacing from a faceplateportion of the envelope bearing a corresponding pattern of red-emissive,blue-emissive and green-emissive phosphor element traids, including fourelectrode suspension devices on the periphery of the electrode, eachcomprising: envelope-mounted means secured in a corner location on theinside of the envelope and on a diagonal of the color selectionelectrode for supporting a corner of a color selection electrode; andelectrode-mounted means for retentively engaging said envelope-mountedmeans, comprising: bracket means secured to said electrode, said bracketmeans including a bimetallic element which, upon heating of theelectrode, deflects to cause the electrode to move nearer to saidfaceplate portion of the envelope, and coupling means including adiscrete, folded-back leaf spring having one leg secured to said bracketmeans and arching radially inwardly therefrom, said coupling meansincluding a provision on an opposed leg of said spring for retentivelyengaging said envelope-mounted means, three of said suspension devicesfixing in the plane of the mask the spatial position of the maskrelative to said faceplate portion, and a redundant fourth suspensiondevice having provision for permitting the fourth corner of the mask toseek an equilibrium position in the plane of the mask.
 8. The apparatusdefined by claim 7 wherein said envelope-mounted means includes a studsecured to the envelope on a diagonal of said electrode and havingtherein a lug-receiving opening on said diagonal, and wherein saidprovision on said opposed leg of said spring comprises a lug forretentively engaging said lug-receiving opening in said stud when theelectrode is operatively mounted in the tube.
 9. The apparatus definedby clAim 8 wherein the redundant fourth suspension device is like theother threee devices except that the lug-receiving opening in said studis a slot elongated in a direction transverse to said diagonal butparallel to said faceplate portion of the envelope.
 10. The apparatusdefined by claim 9 wherein said bracket means has a lug-passing openingformed therein through which said lug passes for operative engagementwith said lug-receiving opening in said stud.
 11. The apparatus definedby claim 10 wherein said spring is pre-stressed such that said opposedleg exerts a load on said bracket means when said device is notsuspending an electrode which is substantially equal to the desiredloading of the electrode by said spring when an electrode is mounted inthe tube.
 12. For use in a rectangular color cathode ray tube, a systemfor suspending on the envelope of the tube at a predetermined precisespacing from a faceplate portion of the envelope which bears a patternof red-emissive, blue-emissive and green-emissive phosphor elementtriads a generally rectangular, frameless color selection electrodehaving formed integrally therewith a forwardly directed skirt angled atapproximately the angle of maximum beam deflection and having a centralregion containing a corresponding pattern of electron-transmissiveapertures, said system including a plurality of electrode suspensiondevices spaced around the electrode, one at each corner thereof, each ofsaid devices comprising: an envelope-mounted stud secured in a preciselocation in a corner of the faceplate portion of the envelope on adiagonal of the electrode for supporting a corner of a color selectionelectrode, said stud having a lug-receiving opening on said diagonal;and electrode-mounted means for retentively engaging said stud,comprising: bracket means externally surrounding and embracing a cornerof the electrode, said bracket having an intermediate portion and endportions secured to the angled skirt on adjoining sides of theelectrode, said bracket means including an edge-bonded bimetallic stripwrapped around the corner of the electrode on the outside thereof which,upon heating of the electrode, deflects in its own plane to cause saidelectrode to move nearer to the faceplate, and a folded-back leaf springhaving one leg secured to said bimetallic strip, said spring archingradially inwardly therefrom, the opposed leg of said spring carrying aradially outwardly facing tapered lug for retentively engaging saidlug-receiving opening in said stud when the electrode is operativelymounted in the tube.
 13. The apparatus defined by claim 12 wherein saidbimetallic strip has a lug-passing opening formed thereon on a diagonalof the electrode through which said lug passes for operative engagementwith said lug-receiving opening in said stud.
 14. The apparatus definedby claim 13 wherein said spring is pre-stressed such that said opposedleg exerts a load on said strip when said device is not suspending anelectrode which is substantially equal to the desired loading of theelectrode by said spring when an electrode is mounted in the tube.